1. Field of the Invention
The present invention relates to a method for manufacturing semiconductor devices having a so-called silicon on insulator (SOI) structure in which a semiconductor layer is provided on an insulating surface.
2. Description of the Related Art
As an alternative to an integrated circuit using a silicon wafer which is manufactured by thinly slicing an ingot of a single crystal semiconductor, an integrated circuit using a semiconductor substrate which is referred to as a silicon-on-insulator (hereinafter also referred to as “SOI”) substrate, in which a thin single crystal semiconductor layer is provided on an insulating surface has been developed. The integrated circuit using an SOI substrate has attracted attention as an integrated circuit which reduces parasitic capacitance between a drain of a transistor and the substrate and improves the performance of a semiconductor integrated circuit.
There are various methods for manufacturing an SOI substrate. As a method in which both quality of an SOI layer and ease of production (throughput) are realized, a method for manufacturing an SOI substrate which is referred to as a Smart Cut (registered trademark) is known. To form the SOI substrate, hydrogen ions are implanted into a silicon wafer (a bond wafer), and the bond wafer is bonded to a base wafer which becomes another base. A silicon layer which is bonded to the base wafer is subjected to heat treatment at approximately 500° C., thereby being separated from the bond wafer.
As an example of a semiconductor device using such an SOI substrate, a semiconductor device disclosed by the present applicant is known (see Patent Document 1: Japanese Published Patent Application No. 2000-012864).
Thus, there has been SOI technology conventionally; however, the area of an SOI substrate has depended on the size of a silicon wafer. Thus, it has not been possible to improve throughput using a large-sized substrate. Meanwhile, there is a method for forming a crystalline silicon layer over a substrate by crystallizing an amorphous silicon layer, which is formed by a film formation method, by laser annealing or the like. However, a single crystal silicon layer cannot be obtained and it has been difficult to perform orientational control or the like of the silicon layer.